Investigation of Potential Therapeutic Effects of New Rapid-Acting Antidepressant Drugs (RAADs) Using Stress-Based Models of Depression

The use of animal models to study mental illnesses, such as depression, requires proper standardization and extensive expertise. Achieving good construct, face, and predictive validity in depression models is quite challenging. Currently, only a few environmental models, mostly based on chronic stress, and a limited number of genetic models fulfill these criteria. In the quest for new antidepressants, initial screening tests are employed as a preliminary step in research. While these tests do not always meet the requirements of a disease model, they are useful for the early identification of substances that may have antidepressant potential, paving the way for further studies based on established models. This approach to discovering antidepressants was originally designed for traditional medications, which typically act by modulating serotonergic, noradrenergic, and dopaminergic systems, and require multi-week administration to produce a therapeutic effect. In contrast, the new antidepressant ketamine offers rapid therapeutic effects following a single dose and exhibits distinctive behavioral outcomes in both screening tests and animal depression models. These effects have inspired a new model for the search for rapid-acting ketamine-like antidepressants. This review presents the behavioral effects of ketamine and discusses the methodologies used in the search for novel rapid-acting antidepressant drugs (RAADs).